The present invention relates to a capacitor trimming system in particular, relates to such a system for trimming a capacitor in a quartz-crystal oscillator.
One of the applications of the capacitor trimmed by the present invention is wrist watch assemblies and/or clock assemblies which are electrically operable and which contain a printed circuit board within a watch case wherein a trimmer capacitor is provided to enable the tuning of an oscillating circuit which, in turn, suitably adjusts the timing mechanism. In view of the design of the watch cases, it will be readily understood that the thickness of the printed circuit panel and the height of components atop the panel must be held to a minimum.
A prior trimmer capacitor for the above applications is shown in U.S. Pat. No. 3,681,664, in which a stator electrode and a rotor electrode parallel to said stator electrode are arranged with suitable dielectric body therebetween. By rotating the rotor electrode, the capacitance is adjusted for the optimum operation of a watch.
However, said prior trimmer capacitor has the disadvantages that the size is not enough small, the capacitance is not stable due to the presence of the mechanical adjustment means, and the adjustment operation can not be automatic but must be carried out by a skilled person. In particular, the lack of the stableness is the important disadvantages since it deteriorates the accuracy of a watch, and that disadvantage is inevitable because of the mechanical structure of said trimmer capacitor. Further, the mechanically adjusted capacitance is apt to change by an external vibration, and then causes the deterioration of the reliability and/or the frequency stability of a watch.